The Effect of Reynolds Number on a Transonic Swept Fan OGV in a Small Turbofan Engine

2012 ◽  
Author(s):  
Toyotaka Sonoda ◽  
Toshiyuki Arima ◽  
Giles Endicott ◽  
Markus Olhofer ◽  
Bernhard Sendhoff
Keyword(s):  
Experimental Data ◽  
Reynolds Number ◽  
Guide Vane ◽  
Low Reynolds Number ◽  
Flow Fields ◽  
Flow Mechanism ◽  
Cfd Model ◽  
Turbofan Engine ◽  
Low Reynolds ◽  
High Reynolds

In this paper, Reynolds effects on a transonic swept fan outlet guide vane (OGV) in a small turbofan engine are evaluated using a CFD model, successfully assessed with respect to experimental data. The flow-fields are evaluated at two Reynolds number conditions, a high Reynolds condition (corresponding to take-off conditions) and a low Reynolds number condition (corresponding to cruise conditions). The CFD results show large differences in the overall OGV performance between these two points. The flow mechanism for the deterioration in the OGV’s performance at the low Reynolds number condition is shown. Finally a new idea for improving the OGV performance is proposed.

A Study of a Modern Transonic Fan Rotor in a Low Reynolds Number Regime for a Small Turbofan Engine

2013 ◽  
Author(s):  
Toyotaka Sonoda ◽  
Rainer Schnell ◽  
Toshiyuki Arima ◽  
Giles Endicott ◽  
Eberhard Nicke
Keyword(s):  
Reynolds Number ◽  
Low Reynolds Number ◽  
Leading Edge ◽  
Reynolds Numbers ◽  
Small Scale ◽  
Turbofan Engine ◽  
Pressure Surface ◽  
Low Reynolds ◽  
High Reynolds ◽  
Transonic Fan

In this paper, Reynolds effects on a modern transonic low-aspect-ratio fan rotor (Baseline) and the re-designed (optimized) rotor performance are presented with application to a small turbofan engine. The re-design has been done using an in-house numerical optimization system in Honda and the confirmation of the performance was carried out using DLR’s TRACE RANS stage code, assessed with respect to experimental data obtained from a small scale compressor rig in Honda. The baseline rotor performance is evaluated at two Reynolds number conditions, a high Reynolds condition (corresponding to a full engine scale size) and a low Reynolds number condition (corresponding to the small scale compressor rig size), using standard ISA conditions. The performance of the optimized rotor was evaluated at the low Reynolds number condition. The CFD results show significant discrepancies in the rotor efficiency (about 1% at cruise) between these two points due to the different Reynolds numbers. The optimized rotor’s efficiency is increased compared to the baseline. A unique negative curvature region close to the leading edge on the pressure surface of the optimized rotor is one of the reasons why the optimized rotor is superior to the baseline.

Free Jet in Confined Combustion Chamber: Numerical Model for Industrial Application in Low NOx Burners

2005 ◽  
Author(s):  
Emanuela Colombo ◽  
Fabio Inzoli ◽  
Enrico Malfa
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Reynolds Number ◽  
Combustion Chamber ◽  
Fluid Dynamic ◽  
Low Reynolds Number ◽  
Turbulence Models ◽  
Dynamic Features ◽  
Low Reynolds ◽  
High Reynolds

The present work is focused on the prediction of the fluid dynamics behaviour for natural gas burners characterized by low NOx emissions. The fluid dynamics in the combustion chamber is investigated in order to look for the condition under which it is possible to obtain a diluted combustion. The experimental data used as reference come from two set of tests related to different isothermal flow behaviour: high Reynolds number (Re = 68000) and lower Reynolds number (Re = 5427). Many turbulence models are examined in order to validate high and low Reynolds case. The k-ω models implemented by Wilcox in 1998 seems to properly predict the fluid dynamics behaviour of the jet for high Reynolds numbers, while, for low Reynolds jets, a modification needs to be introduced. The numerical analysis for low Reynolds number, based on an unstructured 2D axial symmetrical grid, shows that no two-equation turbulence models fit the experimental data for low Reynolds jet. Based on the evidence that at low Reynolds number the hypothesis of homogeneous isotropic small turbulence eddy is not valid a modification of k-ω turbulence model’s closure constant has been proposed. This leads to a better agreement with the experimental data. The results demonstrate that great attention needs to be taken and invested in the identification of the turbulence models used in CFD and in the proper tunneling (of the closure coefficient for the turbulence model) that need to be computed case by case accordingly with the specific turbulence level and fluid dynamic features of the jet itself.

scholarly journals Low-Reynolds-number turbulent boundary layers

1991 ◽  
Vol 230 ◽  
pp. 1-44 ◽  
Author(s):  
Lincoln P. Erm ◽  
Peter N. Joubert
Keyword(s):  
Reynolds Number ◽  
Boundary Layers ◽  
Low Reynolds Number ◽  
Turbulent Boundary Layers ◽  
Stream Velocity ◽  
Wall Region ◽  
Mean Flow ◽  
Low Reynolds ◽  
High Reynolds ◽  
Turbulent Wall

An investigation was undertaken to improve our understanding of low-Reynolds-number turbulent boundary layers flowing over a smooth flat surface in nominally zero pressure gradients. In practice, such flows generally occur in close proximity to a tripping device and, though it was known that the flows are affected by the actual low value of the Reynolds number, it was realized that they may also be affected by the type of tripping device used and variations in free-stream velocity for a given device. Consequently, the experimental programme was devised to investigate systematically the effects of each of these three factors independently. Three different types of device were chosen: a wire, distributed grit and cylindrical pins. Mean-flow, broadband-turbulence and spectral measurements were taken, mostly for values of Rθ varying between about 715 and about 2810. It was found that the mean-flow and broadband-turbulence data showed variations with Rθ, as expected. Spectra were plotted using scaling given by Perry, Henbest & Chong (1986) and were compared with their models which were developed for high-Reynolds-number flows. For the turbulent wall region, spectra showed reasonably good agreement with their model. For the fully turbulent region, spectra did show some appreciable deviations from their model, owing to low-Reynolds-number effects. Mean-flow profiles, broadband-turbulence profiles and spectra were found to be affected very little by the type of device used for Rθ ≈ 1020 and above, indicating an absence of dependence on flow history for this Rθ range. These types of measurements were also compared at both Rθ ≈ 1020 and Rθ ≈ 2175 to see if they were dependent on how Rθ was formed (i.e. the combination of velocity and momentum thickness used to determine Rθ). There were noticeable differences for Rθ ≈ 1020, but these differences were only convincing for the pins, and there was a general overall improvement in agreement for Rθ ≈ 2175.

scholarly journals Prediction of Heat Transfer For Turbulent Flow in Rotating Radial Duct

1995 ◽  
Vol 2 (1) ◽  
pp. 51-58
Author(s):  
P. Tekriwal
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Reynolds Number ◽  
Turbulence Model ◽  
High Reynolds Number ◽  
Low Reynolds Number ◽  
Rotating Flows ◽  
Wall Function ◽  
Model Predictions ◽  
High Reynolds

The objective of the current modeling effort is to validate the numerical model and improve upon the prediction of heat transfer in rotating systems. Low-Reynolds number turbulence model (without the wall function) has been employed for three-dimensional heat transfer predictions for radially outward flow in a square cooling duct rotating about an axis perpendicular to its length. Computations are also made using the standard and extended high-Reynolds number kturbulence models (in conjunction with the wall function) for the same flow configuration. The results from all these models are compared with experimental data for flows at different rotation numbers and Reynolds number equal to 25,000. The results show that the low-Reynolds number model predictions are not as good as the high-Re model predictions with the wall function. The wall function formulation predicts the right trend of heat transfer profile and the agreement with the data is within 30% or so for flows at high rotation number. Since the Navier-Stokes equations are integrated all the way to wall in the case of low-Re model, the computation time is relatively high and the convergence is rather slow, thus rendering the low-Re model as an unattractive choice for rotating flows at high Reynolds number.The extended k-ε turbulence model is also employed to compute heat transfer for rotating flows with uneven wall temperatures and uniform wall heat flux conditions. The comparison with the experimental data available in literature shows that the predictions on both the leading wall and the trailing wall are satisfactory and within 5-25% agreement.

A Numerical Investigation of Transonic Axial Compressor Rotor Flow Using a Low-Reynolds-Number k–ε Turbulence Model

1999 ◽  
Vol 121 (1) ◽  
pp. 44-58 ◽  
Author(s):  
T. Arima ◽  
T. Sonoda ◽  
M. Shirotori ◽  
A. Tamura ◽  
K. Kikuchi
Keyword(s):  
Experimental Data ◽  
Reynolds Number ◽  
Turbulence Model ◽  
Low Reynolds Number ◽  
Axial Compressor ◽  
Numerical Results ◽  
Speed Condition ◽  
Transonic Axial Compressor ◽  
Low Reynolds ◽  
Design Speed

We have developed a computer simulation code for three-dimensional viscous flow in turbomachinery based on the time-averaged compressible Navier–Stokes equations and a low-Reynolds-number k–ε turbulence model. It is described in detail in this paper. The code is used to compute the flow fields for two types of rotor (a transonic fan NASA Rotor 67 and a transonic axial compressor NASA rotor 37), and numerical results are compared to experimental data based on aerodynamic probe and laser anemometer measurements. In the case of Rotor 67, calculated and experimental results are compared under the design speed to validate the code. The calculated results show good agreement with the experimental data, such as the rotor performance map and the spanwise distribution of total pressure, total temperature, and flow angle downstream of the rotor. In the case of Rotor 37, detailed comparisons between the numerical results and the experimental data are made under the design speed condition to assess the overall quality of the numerical solution. Furthermore, comparisons under the part-speed condition are used to investigate a flow field without passage shock. The results are well predicted qualitatively. However, considerable quantitative discrepancies remain in predicting the flow near the tip. In order to assess the predictive capabilities of the developed code, computed flow structures are presented with the experimental data for each rotor and the cause of the discrepancies is discussed.

scholarly journals Numerical Predictions of Uniform CO2 Corrosion in Complex Fluid Domains Using Low Reynolds Number Models

Metals ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 1001
Author(s):  
Haijun Hu ◽  
Hao Xu ◽  
Changmeng Huang ◽  
Xing Chen ◽  
Xiufeng Li ◽  
...  
Keyword(s):  
Experimental Data ◽  
Mass Transfer ◽  
Reynolds Number ◽  
Low Reynolds Number ◽  
Co2 Corrosion ◽  
Aqueous Corrosion ◽  
Corrosion Rates ◽  
Complex Fluid ◽  
Low Reynolds ◽  
Near Wall

To get the knowledge of local corrosion, thinning is useful for developing targeted inspection plans for pipe components in the oil/gas industry. Aiming at this object, this work presents a computer fluid dynamics (CFD) method to predict CO2 aqueous corrosion in complex fluid domains. The processes involved in CO2 aqueous corrosion, including flow dynamics, mass transfer, chemical reactions, and electrochemical reactions, are modeled and simulated by a commercial CFD software of Fluent V15.0 (Version, manufacturer, city, country). Mass transfer in the straight pipe flow and jet impinging flow are simulated using three low-Reynolds-number turbulent models (Abe–Kondoh–Nagano k − ε model, Change–Hsieh–Chenk k − ε model, and k − ε shear stress transport model). The flow domains are meshed by grids with the first near-wall node at the position at y+ = 0.1. Comparisons between simulations and experimental data show the Abe–Kondoh–Nagano model provides the best predictions of near-wall flow and mass transfer. Thus, it is used to predict CO2 aqueous corrosion. Corrosion rates of dissolved CO2 in straight pipes and a jet impinging are predicted. The predicted corrosion rates are compared with experimental data and results derived from commercial software, Multicorp V5.2.105. The results show that predicted corrosion rates are reasonable. The locations of the highest corrosion rate for a jet impinging system are revealed.

scholarly journals A Numerical Investigation of Transonic Axial Compressor Rotor Flow Using a Low Reynolds Number k-ε Turbulence Model

1997 ◽  
Author(s):  
Toshiyuki Arima ◽  
Toyotaka Sonoda ◽  
Masatoshi Shirotori ◽  
Atsuhiro Tamura ◽  
Kazuo Kikuchi
Keyword(s):  
Experimental Data ◽  
Reynolds Number ◽  
Turbulence Model ◽  
Low Reynolds Number ◽  
Axial Compressor ◽  
Numerical Results ◽  
Speed Condition ◽  
Transonic Axial Compressor ◽  
Low Reynolds ◽  
Design Speed

We have developed a computer simulation code for three-dimensional viscous flow in turbomachinery based on the time-averaged compressible Navier-Stokes equations and a low Reynolds number k-ε turbulence model. It is described in detail in this paper. The code is used to compute the flow fields for two types of rotor (a transonic fan NASA Rotor 67 and a transonic axial compressor NASA rotor 37), and numerical results are compared to experimental data based on aerodynamic probe and laser anemometer measurements. In the case of Rotor 67, calculated and experimental results are compared under the design speed to validate the code. The calculated results show good agreement with the experimental data, such as the rotor performance map and the spanwise distribution of total pressure, total temperature, and flow angle downstream of the rotor. In the case of Rotor 37, detailed comparisons between the numerical results and the experimental data are made under the design speed condition to assess the overall quality of the numerical solution. Furthermore, comparisons under the part speed condition are used to investigate a flow field without passage shock. The results are well predicted qualitatively. However, considerable quantitative discrepancies remain in predicting the flow near the tip. In order to assess the predictive capabilities of the developed code, computed flow structures are presented with the experimental data for each rotor and the cause of the discrepancies is discussed.

Advanced High Turning Compressor Airfoils for Low Reynolds Number Condition: Part 2 — Experimental and Numerical Analysis

2003 ◽  
Author(s):  
Heinz-Adolf Schreiber ◽  
Wolfgang Steinert ◽  
Toyotaka Sonoda ◽  
Toshiyuki Arima
Keyword(s):  
Boundary Layer ◽  
Reynolds Number ◽  
Guide Vane ◽  
Incidence Angle ◽  
Low Reynolds Number ◽  
Aerodynamic Characteristics ◽  
Low Loss ◽  
Design And Optimization ◽  
Negative Effect ◽  
Low Reynolds

Part 1 of this paper describes the design and optimization of two high turning subsonic compressor cascades operating as an outlet guide vane (OGV) behind a single stage low pressure turbine at low Reynolds number condition (Re = 1.3×105). In the numerical optimization algorithm, the design point and off-design performance has been considered in an objective function to achieve a wide low loss incidence range. The objective of the present paper is to examine some of the characteristics describing the new airfoils as well as to prove the reliability of the design process and the applied flow solver. Some aerodynamic characteristics for the two new airfoils and a conventional controlled diffusion airfoil (CDA), have been extensively investigated in the cascade wind tunnel of DLR Cologne. For an inlet Mach number of 0.6 the effect of Reynolds number and incidence angle on each airfoil performance is discussed, based on experimental and numerical results. For an interpretation of the airfoil boundary layer behavior, results of some boundary layer calculations are compared to oil flow visualization pictures. The design goal of an increased low loss incidence range at low Reynolds number condition could be confirmed without having a negative effect on the high Reynolds number region.

Sign in / Sign up

Export Citation Format

Share Document